The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various structures and methods to form power factor correction circuits. The power factor was generally recognized as a measure of the difference between the voltage and current waveforms of an alternating current (AC) waveform. Differences between the current and voltage waveforms resulted in low efficiency utilization of the supplied AC power. Power factor correction circuits were utilized to more closely align the shape of the current and voltage waveforms in order to provide higher efficiency. Examples of power factor correction circuits are disclosed in U.S. Pat. No. 5,134,355 issued to Roy Alan Hastings on Jul. 28, 1992; U.S. Pat. No. 5,359,281 issued to Barrow et al on Oct. 25, 1994; and U.S. Pat. No. 5,502,370 issued to Hall et al on Mar. 26, 1996 all of which are hereby incorporated herein by reference.
One problem with the previous power factor control circuits was the transient response time. In order to reduce ripple in the output voltage, the bandwidth of the control loop generally was keep very low. The bandwidth of the control loop generally was about ten times less than the frequency of the AC input voltage and typically was limited to about ten to twelve Hz (10-12 Hz). Because of the low bandwidth, the previous power factor correction circuits generally had a slow response to transients on the output voltage.
Accordingly, it is desirable to have a method of forming a power factor correction device that has a wider loop bandwidth and that more quickly responds to output voltage transients.
For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain N-channel or P-Channel devices, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention. It will be appreciated by those skilled in the art that the words during, while, and when as used herein are not exact terms that mean an action takes place instantly upon an initiating action but that there may be some small but reasonable delay, such as a propagation delay, between the reaction that is initiated by the initial action.